Certain constructors have the maximum number of automatic adjustments on the machines for folding and notching the cardboard, but it is nonetheless necessary to devote considerable time to placement of the blocks on the printers and to the washing of their inking cylinders. In the case of overhead printing flexographic printers, this drawback is offset by taking advantage, when possible, of the passage of a series of boxes which are to be printed with a reduced number of colors, for example one instead of two, to disengage the unused block-holder cylinders of the printing modules and to carry out the positioning of further blocks on the latter while the machine operates with said reduced color series.
Such a solution is unfortunately, through lack of space and possibility of access, not applicable to bottom-printing flexographic printers, the use of which appears to be more and more desirable with the development of entirely automatic machines.
One solution which could be envisaged to resolve this problem would be a modular construction with complete lateral displacement of the unused printing elements during the passage of the reduced color series. One or several gaps would then be created in the machine, which it would be necessary to fill by bringing together all the elements remaining in the machine so that they may be coupled. Such a solution would have the drawback of constantly modifying the length of the machine and, in addition, would occupy much space on the floor since it would be necessary to move each complete printing element laterally, including, in particular, its electrical panels, and hence constituting a rather bulky unit.